Upgrade babel and add babel runtime (#6401)

In this diff I upgraded to babel 7, enabled class properties loose mode
and added babel runtime which allows to reuse helpers between all
packages.

For CJS bundles I still use inlined helpers.

packages/react-router-config/.size-snapshot.json

@@ -1,26 +1,26 @@
 {
   "esm/react-router-config.js": {
-    "bundled": 1746,
-    "minified": 1013,
-    "gzipped": 473,
+    "bundled": 1467,
+    "minified": 765,
+    "gzipped": 384,
     "treeshaked": {
       "rollup": {
-        "code": 35,
-        "import_statements": 35
+        "code": 78,
+        "import_statements": 78
       },
       "webpack": {
-        "code": 1066
+        "code": 1128
       }
     }
   },
   "umd/react-router-config.js": {
-    "bundled": 2383,
-    "minified": 1261,
-    "gzipped": 601
+    "bundled": 2457,
+    "minified": 1163,
+    "gzipped": 588
   },
   "umd/react-router-config.min.js": {
-    "bundled": 2383,
-    "minified": 1261,
-    "gzipped": 601
+    "bundled": 2457,
+    "minified": 1163,
+    "gzipped": 588
   }
 }

packages/react-router-config/modules/.babelrc.js

@@ -0,0 +1,4 @@
+module.exports = {
+  presets: [["@babel/env", { loose: true }], "@babel/react"],
+  plugins: ["dev-expression"]
+};

packages/react-router-config/modules/index.js

@@ -1,2 +1,2 @@
-export matchRoutes from "./matchRoutes";
-export renderRoutes from "./renderRoutes";
+export { default as matchRoutes } from "./matchRoutes";
+export { default as renderRoutes } from "./renderRoutes";